A color picture tube has a glass envelope that comprises a neck, a funnel and a rectangular faceplate panel. The faceplate panel includes a viewing faceplate that is surrounded by a peripheral sidewall. The sidewall of the faceplate panel is sealed to a large end of the funnel by a glass frit. The surfaces of the facing ends of the panel sidewall and the funnel are called their seal lands. Between the panel sidewall and the panel faceplate, there is a transition zone that includes a blend radius. Recently, there has been an effort to expand or stretch the size of a tube screen by reducing the blend radius at least in the corners of a tube, while not enlarging the overall exterior size and dimensions of the tube.
One of the problems that occurs when the blend radius of a panel is changed is that the inner surface of the panel sidewall become less sloped relative to the sidewall seal land, i.e., .O slashed. in FIG. 3 gets smaller. This shallower slope creates a problem in removing the panel forming plunger from the panel during panel forming in a glass factory. This problem cannot be solved by making the entire panel sidewall thinner, because panel sidewall thickness affects the strength of the panel, and panel strength must be maintained for the tube to withstand the atmospheric load on it and to meet safety criteria. Therefore, there is a need for a new panel design that will retain strength, and maintain a large slope .O slashed. necessary for ease of removal from a mold during fabrication.